Method of removing structure directing agents from molecular sieves

ABSTRACT

A structure directing agent is removed from a microporous solid at a temperature below the temperature that would cause the structure directing agent to decompose by cleaving the structure directing agent within the pores of the microporous solid, at a temperature below the temperature that would cause the structure directing agent to decompose, into two or more fragments and removing the fragments from the pores of the microporous solid at a temperature below the temperature that would cause the structure directing agent or its fragments to decompose.

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/257,826, filed Dec. 22, 2000.

BACKGROUND OF THE INVENTION

[0002] Microporous solids such as molecular sieves (e.g., zeolites) areoften synthesized using a “structure directing agent” (SDA). The SDAapparently assists in organizing the atoms of the molecular sieve into aparticular crystalline topology. The SDA may typically be an organicamine, quaternary ammonium compound or organometallic compound. Once themicroporous solid is synthesized, the SDA is in the pores of themicroporous solid and is quite often spatially trapped. In order toremove the SDA from the pores, the microporous solid is normally heatedto a very high temperature, i.e., calcined, to decompose the SDA andrelease the smaller decomposition produces from the pores. However,calcination can have deleterious effects on the microporous solid, anddestroys the SDA, preventing its reuse. Calcination may also causeenvironmental problems due to the effluent gases formed.

[0003] It would, therefore, be desirable to be able to remove the SDAfrom a microporous solid without having to calcine it. It would also bedesirable to be able to recover the SDA in a form such that it can bereused.

SUMMARY OF THE INVENTION

[0004] In accordance with the present invention, there is provided amethod of removing a structure directing agent from a microporous solidat a temperature below the temperature that would cause the structuredirecting agent to decompose comprising cleaving the structure directingagent within the pores of the microporous solid, at a temperature belowthe temperature that would cause the structure directing agent todecompose, into two or more fragments and removing the fragments fromthe pores of the microporous solid at a temperature below thetemperature that would cause the structure directing agent or itsfragments to decompose.

[0005] Further provided in accordance with the present invention is amethod of removing a structure directing agent from a porous molecularsieve at a temperature below the temperature that would cause thestructure directing agent to decompose comprising cleaving the structuredirecting agent within the pores of the molecular sieve, at atemperature below the temperature that would cause the structuredirecting agent to decompose, into two or more fragments and removingthe fragments from the pores of the molecular sieve at a temperaturebelow the temperature that would cause the structure directing agent orits fragments to decompose. Preferably, the SDA is decomposed intofragments that can be recombined ex situ for recyclable use.

[0006] The present invention also provides a method of making a porous,crystalline molecular sieve comprising:

[0007] (a) preparing an aqueous solution from (1) sources of an alkalimetal oxide, alkaline earth metal oxide or mixtures thereof; (2) sourcesof an oxide selected from the oxides of aluminum, iron, gallium, indium,titanium, or mixtures thereof; (3) sources of an oxide selected fromoxides of silicon, germanium or mixtures thereof; and (4) a structuredirecting agent capable of forming the molecular sieve;

[0008] (b) maintaining the aqueous solution under conditions sufficientto form porous crystals of the molecular sieve which contain thestructure directing agent in the pores; and

[0009] (c) cleaving the structure directing agent, at a temperaturebelow the temperature that would cause the structure directing agent todecompose, into two or more fragments and removing the fragments fromthe molecular sieve at a temperature below the temperature that wouldcause the structure directing agent or its fragments to decompose.

[0010] The present invention also provides a method of making a porous,crystalline molecular sieve comprising:

[0011] (a) preparing an aqueous solution from (1) sources of an alkalimetal oxide, alkaline earth metal oxide or mixtures thereof; (2) sourcesof an oxide selected from the oxides of aluminum, iron, gallium, indium,titanium, or mixtures thereof; (3) sources of an oxide selected fromoxides of silicon, germanium or mixtures thereof; and (4) a structuredirecting agent capable of forming the molecular sieve; and (5) an aminecomponent comprising at least one amine containing one to eight carbonatoms, ammonium hydroxide and mixtures thereof;

[0012] (b) maintaining the aqueous solution under conditions sufficientto form porous crystals of the molecular sieve which contain thestructure directing agent and the amine component in the pores;

[0013] (c) removing the amine component from the pores of the molecularsieve at a temperature below the temperature that would cause thestructure directing agent or the amine component to decompose; and

[0014] (d) cleaving the structure directing agent, at a temperaturebelow the temperature that would cause the structure directing agent todecompose, into two or more fragments and removing the fragments fromthe molecular sieve at a temperature below the temperature that wouldcause the structure directing agent or its fragments to decompose.

[0015] Further provided by the present invention is a method of making amicroporous solid comprising:

[0016] (a) preparing a reaction mixture comprising at least one activesource of reactants required to produce the microporous solid, astructure directing agent capable of forming said microporous solid, andsufficient water to shape said mixture into a self-supporting shape;

[0017] (b) heating said reaction mixture at crystallization conditionsand in the absence of an external liquid phase for sufficient time toform the microporous solid containing the structure directing agent; and

[0018] (c) cleaving the structure directing agent, at a temperaturebelow the temperature that would cause the structure directing agent todecompose, into two or more fragments and removing the fragments fromthe molecular sieve at a temperature below the temperature that wouldcause the structure directing agent or its fragments to decompose.

[0019] Also provided in accordance with this invention is a method ofmaking a microporous solid comprising:

[0020] (a) preparing a reaction mixture comprising at least one activesource of reactants required to produce the microporous solid, astructure directing agent capable of forming said microporous solid, anamine component comprising at least one amine containing one to eightcarbon atoms, ammonium hydroxide and mixtures thereof, and sufficientwater to shape said mixture into a self-supporting shape;

[0021] (b) heating said reaction mixture at crystallization conditionsand in the absence of an external liquid phase for sufficient time toform the microporous solid containing the structure directing agent andthe amine component; and

[0022] (c) removing the amine component from the pores of the molecularsieve at a temperature below the temperature that would cause thestructure directing agent or the amine component to decompose; and

[0023] (d) cleaving the structure directing agent, at a temperaturebelow the temperature that would cause the structure directing agent todecompose, into two or more fragments and removing the fragments fromthe molecular sieve at a temperature below the temperature that wouldcause the structure directing agent or its fragments to decompose.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0024] The present invention provides a method for removing an SDA froma microporous solid in a manner that does not require the use of hightemperatures. As used herein, the term “microporous solid” refers tosolid materials that contain pores within their structure. The size ofthe pores can range from about 3 Angstroms to about 20 Angstroms indiameter (normally measured along the longest axis). The microporoussolids are typically crystalline materials with a particular crystaltopology. Examples of microporous solids include molecular sieves,zeolites, silicoaluminophosphates (SAPO's), aluminophosphates (ALPO's),inorganic oxides, inorganic sulfides and hetero polytungstates. Specificexamples include, but are not limited to zeolite beta, ZSM-5, SSZ-25,SM-3, SSZ-32, SSZ-13, SSZ-33 and ZSM-23.

[0025] As used herein, the term “structure directing agent” or “SDA”refers to compounds found within the pores of the microporous solidafter it is made. Sometimes referred to as a “guest molecule” the SDA isfound inside the lattice of the microporous solid. The SDA has a closespatial fit within the micropore regions of the microporous solid. It isbelieved the SDA assists in arranging the atoms of the microporous solidinto a particular pattern. Often, the SDA can specify nucleation of onemicroporous crystalline solid over others. In some cases, an SDA mightbe associated with the formation of only a single microporous structure.Normally, an SDA is large enough in relation to the size of the pores ofthe microporous solid that it becomes trapped inside the pores when themicroporous solid is formed. In many cases, the only way to remove theSDA from the pores of the microporous solid is to heat the microporoussolid to a temperature at which the SDA decomposes (i.e., calcining themicroporous solid). In accordance with the present invention, the SDA isremoved from the microporous solid by “cleaving” it within the pores ofthe microporous solid. The term “cleaving” as used herein means breakingthe SDA into two or more fragments at a temperature below thetemperature at which the SDA decomposes. The cleaving can beaccomplished by breaking covalent bonds within the SDA, or by otherwisefragmenting the SDA, such as by removing ligands from the metal, atom inan organometallic compound. The SDA's fragments are then small enough inrelation to the pores of the microporous solid that they can be removedwithout the need for calcination. The present invention is especiallyuseful for SDA's that can not be removed from the microporous solid bynon-thermal techniques such as solvent extraction.

[0026] The fragments of the cleaved SDA can be removed from the pores ofthe microporous solid at a temperature of less than about 300° C. Thishelps avoid possible alteration or destruction of the microporous solidthat may occur at typical calcination temperatures of about 350 C. toabout 400 C. or above, as well as avoid the total destruction of theSDA.

[0027] Once the SDA has been cleaved, its fragments can be removed fromthe pores of the microporous solid by techniques such as solventextraction, vaporization, sublimation or vacuum evaporation. If thetechnique for removing the SDA fragments is solvent extraction, thepreferred solvents are polar solvents when the SDA is charged (e.g., theSDA is a quaternary ammonium compound). Examples of such solventsinclude dimethylformamide (DMF) and ethylene glycol. Once the fragmentshave been extracted, the microporous solid can be washed with water anddried.

[0028] Conditions (temperature, pressure, etc.) for removal of the SDAfragments from the microporous solid will vary depending upon theparticular microporous solid, the size of the SDA relative to the pores,the size of the SDA fragments relative to the size of the pores, and thelike.

[0029] The microporous solids useful in the present invention are solidshaving internal pores in their structure. The size of the pores mayrange from about 3 Angstroms to about 20 Angstroms. Often, themicroporous solids have a particular crystalline topology. Examples ofmicroporous solids that can be used in this invention include, but arenot limited to molecular sieves, zeolites, silicoaluminophosphates(SAPO's), aluminophosphates (ALPO's), inorganic oxides, inorganicsulfides and hetero polytungstates. Microporous solids other than thoselisted above may also be useful.

[0030] The manner of making the SDA-containing microporous solid is notcritical. Standard synthesis techniques can be used. For example, whenthe microporous solid is a silicate or metallosilicate zeolite, thezeolite can be made by forming a reaction mixture from sources of alkaliand/or alkaline earth metal (M) cations with valences n (i.e., 1 or 2);sources of an oxide of aluminum, boron, iron, gallium, indium, titanium,vanadium or mixtures thereof (W); sources of an oxide of silicon,germanium or mixtures thereof (Y); an SDA (Q); and water, said reactionmixture having a composition in terms of mole ratios within thefollowing ranges: Reactants General Preferred YO₂/W_(a)O_(b)   20-∞  25-90 OH⁻/YO₂ 0.10-0.50 0.15-0.30 Q/YO₂ 0.05-0.50 0.10-0.30M_(2/n)/YO₂ 0.02-0.40 0.01-0.30 H₂O/YO₂   10-100   25-50

[0031] where Y is silicon germanium or a mixture thereof, W is aluminum,boron, gallium, indium, iron, titanium, vanadium or mixtures thereof, Qis an SDA capable of forming the desired molecular sieve, M is an alkalimetal cation, alkaline earth metal cation or mixtures thereof, n is thevalence of n (i.e., 1 or 2), a is 1 or 2, and b is 2 when a is 1 (i.e.,W is tetravalent) and b is 3 when a is 2 (i.e., W is trivalent).

[0032] Typical sources of aluminum oxide for the reaction mixtureinclude aluminates, alumina, hydrated aluminum hydroxides, and aluminumcompounds such as AlCl₃ and Al₂(SO₄)₃. Typical sources of silicon oxideinclude silica hydrogel, silicic acid, colloidal silica, tetraalkylorthosilicates, silica hydroxides, and fumed silicas. Gallium, iron,boron, indium, titanium, vanadium and germanium can be added in formscorresponding to their aluminum and silicon counterparts. Trivalentelements stabilized on silica colloids are also useful reagents.

[0033] In preparing the zeolites, the reactants and the SDA aredissolved in water and the resulting reaction mixture is maintained atan elevated temperature until crystals are formed. The hydrothermalcrystallization is usually conducted under autogenous pressure, at atemperature between 100° C. and 200° C., preferably between 135° C. and160° C. The crystallization period is typically greater than 1 day andpreferably from about 3 days to about 20 days. The reaction mixture ispreferably stirred during crystallization.

[0034] Once the zeolite crystals have formed, the solid product isseparated from the reaction mixture by standard mechanical separationtechniques, such as filtration. The crystals are water-washed and thendried, e.g., at 90° C. to 150° C. for from 8 to 24 hours, to obtain theas-synthesized zeolite crystals. The drying step can be performed atatmospheric or subatmospheric pressures.

[0035] During the hydrothermal crystallization step, the crystals can beallowed to nucleate spontaneously from the reaction mixture. Thereaction mixture can also be seeded with crystals of the desired zeoliteboth to direct, and accelerate the crystallization, as well as tominimize the formation of any undesired crystalline phases. When seedcrystals are used, typically about 0.5% to about 5.0% by weight (basedon the weight of silica used in the reaction mixture) of the seedcrystals are added.

[0036] Due to the unpredictability of the factors which controlnucleation and crystallization in the art of crystalline oxidesynthesis, not every combination of reagents, reactant ratios, andreaction conditions will result in crystalline products. Selectingcrystallization conditions which are effective for producing crystalsmay require routine modifications to the reaction mixture or to thereaction conditions, such as temperature, and/or crystallization time.Making these modifications are well within the capabilities of oneskilled in the art.

[0037] The SDA can also be used in combination with an amine componentto prepare the molecular sieve. The use of a combination of an SDA andan amine component is disclosed in U.S. Pat. No. 5,785,947, issued Jul.28, 1998 to Zones et al., which is incorporated by reference herein inits entirety. The use of the combination of an SDA and amine componentprovides several advantages including permitting the use of less SDA. Italso allows the amine to be removed from the pores of the synthesizedzeolite by relatively simple techniques, such as solvent extraction.Removal of the amine from the pores of the zeolite makes room in thepores for a reactant to enter the pores and cleave the SDA.

[0038] When a combination of an SDA and amine component is used, thereaction mixture should have a composition in terms of mole ratiosfalling within the following ranges: Broad Preferred M_(2/n)/YO₂0.01-0.50 0.10-0.20 OH⁻/YO₂ 0.01-0.60 0.10-0.30 H₂O/YO₂  10-120 20-50Q/YO₂ 0.02-1.00 0.02-0.10 YO₂/WaOb  10-200  15-120 Z/YO₂ 0.05-1.000.20-0.40

[0039] where M, n, Y, Q, W, a, and b are as defined above and Z is anamine component comprising at least one amine chosen from aminescontaining from one to eight carbon atoms, ammonium hydroxide andmixtures thereof.

[0040] The amine component comprises at least one amine chosen fromamines containing from one to eight carbon atoms, ammonium hydroxide andmixtures thereof. These amines tend to be smaller than the SDA used toprepare the zeolite. As used herein, the term “smaller”, when used withrespect to the amine component, means that the amine is lower inmolecular weight than the SDA and typically is no larger physically thanthe SDA. Non-exclusive examples of these amines include isopropylamine,isobutylamine, n-butylamine, piperidine, 4-methylpiperidine,cyclohexylamine, 1,1,3,3-tetramethyl butylamine, cyclopentylamine andmixtures of such amines.

[0041] Silicoaluminophosphates can be prepared by conventionaltechniques such as those disclosed in U.S. Pat. No. 4,440,871, issuedApr. 3, 1984 to Lok et al., and U.S. Pat. No. 4,493,424, issued Jul. 24,1990 to Miller, both of which are incorporated herein by reference intheir entirety. The overall procedure is similar to that described abovefor zeolites using a reaction mixture composition expressed in terms ofmolar oxide ratios as follows:

aX₂O:(Si_(x)Al_(y)P_(z))O₂:hH₂O

[0042] where X is an SDA, a has a value great enough to constitute aneffective concentration and is in the range of from greater than 0 to 3,h has a value of from 0 to 500, x, y and z represent the mole fractions,respectively, of silicon, aluminum and phosphorus in the SAPconstituent, and each has a value of at least 0.01. The reaction mixturemay also contain alkali metal cations. Typically, the source ofphosphorus is phosphoric acid, the aluminum source may be an aluminumalkoxide, and silica is a typical source of silicon.

[0043] The aluminophosphates can be prepared in a manner very similar tothat used to make SAPO's, except that no silicon is present. Such amethod is disclosed in U.S. Pat. No. 4,310,440, issued Jan. 12, 1982 toWilson, et al., which is incorporated by reference herein in itsentirety. The reaction mixture can have a composition, in terms of molarratios of oxides, as follows:

Al₂O₃:±0.5P₂O₅:7-100H₂O

[0044] and containing from about 0.2 to 2.0 moles of an SDA per mole ofAl₂O₃. Starting materials can be the same as those used to make SAPO's.

[0045] The methods described above for making the various microporoussolids generally involve a starting mixture that is an aqueous solutionor gel. However, the microporous solids can also be made by the methoddisclosed in U.S. Pat. No. 5,514,362, issued May 7, 1996 to Miller, andU.S. Pat. No. 5,558,851, issued Sep. 24, 1996 to Miller, both of whichare incorporated herein by reference in their entirety. This method usesconsiderably less liquid than the traditional solution methods. Inaccordance with the method disclosed in those patents, the microporoussolid can be made by

[0046] a. preparing a reaction mixture comprising at least one activesource of reactants required to produce the microporous solid, astructure directing agent capable of forming said crystalline zeolite,and sufficient water to shape said mixture into a self-supporting shape;and

[0047] b. heating said reaction mixture at crystallization conditionsand in the absence of an external liquid phase for sufficient time toform the microporous solid containing the structure directing agent.

[0048] Like the microporous solids made by conventional solutionmethods, the microporous solid resulting from this process will containthe SDA in its pores. The SDA can then be removed from the pores of themicroporous solid by cleaving the SDA within the pores of themicroporous solid and removing the SDA fragments in the manner describedherein.

[0049] One type of SDA useful in the present invention areammonium-acetals. As used herein, the term “ammonium-acetal” refers toorganic compounds that contain both a quaternary ammonium portion and anacetal portion (the acetal portion being two ether groups attacheddirectly to the same carbon atom). Examples of ammonium-acetals include,but are not limited

[0050] to, compounds having the following general formulas:

[0051] where R¹, R² and R³ are each independently lower alkyl (e.g.,methyl, ethyl, propyl or butyl), preferably methyl, and R⁴ and R⁵ areeach independently lower alkyl (e.g., methyl, ethyl, propyl or butyl),preferably ethyl.

[0052] where R⁶ and R⁷ are each independently lower alkyl (e.g., methyl,ethyl, propyl or butyl), or R⁶ and R⁷ together form a five or sixmembered, substituted or unsubstituted ring with the nitrogen atom, andR⁸ and R⁹ are each independently lower alkyl (e.g., methyl, ethyl,propyl or butyl), or R⁸ and R⁹ together are —CH₂CH₂—, i.e., they form aform a five membered ring.

[0053] Examples of specific ammonium-acetals include, but are notlimited to, the following compounds:

[0054] One method of cleaving the ammonium-acetals is by contacting themwith HCl. This can be done by passing HCl through water to produce gasphase water saturated with HCl. The microporous solid containing theammonium-acetal is then contacted with the gas phase water saturatedwith HCl at elevated temperature (i.e., high enough to maintain thewater in the gaseous phase, e.g., about 120° C.). The ammonium-acetal iscleaved into an ammonium-diol (i.e., the two ether groups in theammonium-acetal have been converted to hydroxyls) and two moles ofalcohol.

[0055] One advantage of using an ammonium-acetal as the SDA is that thereaction which cleaves it into an ammonium-diol and alcohol is readilyreversible to produce the original ammonium-acetal. Thus, if theammonium-diol is reacted with alcohol, the original SDA can berecreated.

EXAMPLES Example 1 Synthesis of 2,2-DiethoxyethyltrimethylammoniumCation (SDA 1)

[0056] Dimethylaminoacetaldehyde diethyl acetal is dissolved in 70 ml ofchloroform. 17.60 Grams (0.124 mol) of iodomethane is added to theresulting solution over ten minutes. The resulting solution is stirredovernight. Diethyl ether is added to the solution. Yellow solids formand are collected by filtration and washed with ether. The solids arerecrystallized from hot acetone/diethyl ether. A small amount ofmethanol is added to aid dissolution. Bio-Rad AG1-X8 anion exchangeresin is used to convert the iodide salt to the corresponding hydroxideform in 100% yield.

Example 2 Dissociation of SDA 1

[0057]128 ml of 0.328 M SDA 1 (hydroxide form) is evaporated usingrotovap. The resulting solution contains 8.11 grams of SDA 1 and 16.22grams of water. This solution is mixed with 100 ml of IN HCl andrefluxed for two hours at 100° C. Upon cooling, the solution is analyzedby NMR which shows the ethoxy groups in SDA 1 are converted to alcohols.

[0058] This example demonstrates that SDA 1 can be cleaved into a dioland ethanol.

Example 3 Doping of SDA 1 into Zeolite Beta

[0059] 0.31 Gram of preformed calcined zeolite beta is stirred in 50 mlof 0.01 M solution of SDA 1 for six hours at room temperature. The pH is11.94. The doped zeolite is washed with deionized water and dried. 0.29Gram of preformed calcined silica zeolite beta is stirred in 500 ml of0.0002 M SDA 1 solution for six hours at room temperature. The pH is10.25. The resulting doped zeolite is washed with deionized water anddried.

[0060] NMR analysis indicates that SDA 1 is doped into the pores of thezeolite beta.

Example 4 Cleavage of SDA 1 Within the Pores of Zeolite Beta

[0061] 0.60 Gram of boron zeolite beta doped with SDA 1 in a mannersimilar to that of Example 3 is put in a reactor and the temperature ofthe reactor is raised to 120° C. After Ar purge for one hour, HCl gas(produced by passing HCl gas through a vessel containing water toproduce water in the gas phase that is saturated with HCl) is introducedinto the reactor. The flow of HCl-saturated water in the gas phase ismaintained for one hour. The reactor is purged again with Ar for onehour.

[0062] NMR analysis of the resulting product shows that the SDA 1 acetalis completely cleaved inside the zeolite beta pores into a diol andethanol.

Example 5 Synthesis of SDA 3

[0063] 4.00 Grams (0.028 mol) of 1,4-dioxa-8-azaspiro[4,5]decane, 8.01grams (0.043 mol) of tributylamine, and 30 ml of methanol are mixed in aflask and 12.20 grams (0.086 mol) of iodomethane is added dropwise overa period of ten minutes. The mixture is refluxed for five days at roomtemperature. Yellow solids are produced. After adding ethyl ether to themixture, the solids are filtered and washed with ethyl ether. The solidsare recrystallized from hot acetone/methanol. Iodine salts are convertedto the corresponding hydroxide form in 90.2% yield using Bio-Rad AG1-X8anion exchange resin. The resulting product is SDA 3.

Example 6 Synthesis of ZSM-5 Using SDA 3

[0064] 0.20 Gram (0.0027 mol) of isobutylamine is added to a mixture of0.095 gram (0.0005 mol) of hydroxide form SDA 3 and 11.40 gram (0.6326mol) of water. ). 0.2 Gram (0.0036 mol) of potassium hydroxide and 0.083gram (0.0011 mol) of aluminum hydroxide (Reheis 2000) are added to themixture which is stirred to get a clear solution. 0.9 Gram (0.0150 mol)of silica (Cab-O-Sil M5) is added to the solution which is stirred fortwo hours to get a homogeneous gel. The resulting mixture is chargedinto a rotating Teflon lined autoclave and heated at 443° K for sixdays. After crystallization, the autoclave is cooled to roomtemperature. The solid product is collected by filtration, repeatedlywashed with deionized water and dried overnight. X-ray diffractionindicates the product to be ZSM-5. NMR analysis shows that the pores ofthe ZSM-5 contain both SDA 3 and isobutylamine.

Example 7 Synthesis of SDA 4

[0065] 10.02 Grams of 1,4-dioxa-8-azaspiro[4,5]decane (98%) and 18.54grams of tributylamine (99%) are added to 100ml of methanol. 16.10 Gramsof 1,4-dibromopentane (97%) is added dropwise to the mixture in a cooledice bath. The resulting mixture is stirred for several hours and the icebath is removed. The mixture is stirred for five days more at roomtemperature. It is checked that the reaction is completed by thin layerchromatography. After the resulting solution is concentrated in a rotaryevaporator, the residual oil is re-extracted with chloroform. Thesolution is concentrated again. Acetone is added to the concentratedsolution, and white solids are obtained. These solid are recrystallizedfrom hot methanol/acetone by a rotary evaporation. Bio-Rad AGI-X8 anionexchange resin is used to convert the bromide salt to the correspondinghydroxide form. The OH— concentration is determined by titration.

What is claimed is:
 1. A method of removing a structure directing agentfrom a microporous solid at a temperature below the temperature thatwould cause the structure directing agent to decompose comprisingcleaving the structure directing agent within the pores of themicroporous solid, at a temperature below the temperature that wouldcause the structure directing agent to decompose, into two or morefragments and removing the fragments from the pores of the microporoussolid at a temperature below the temperature that would cause thestructure directing agent or its fragments to decompose.
 2. The methodof claim 1 wherein the microporous solid is an inorganic oxide,inorganic sulfide, molecular sieve, zeolite, aluminophosphate,silicoaluminophosphate or hetero polytungstate.
 3. The method of claim 2wherein the microporous solid is an inorganic oxide or inorganicsulfide.
 4. The method of claim 2 wherein the microporous solid is amolecular sieve.
 5. The method of claim 2 wherein the microporous solidis a zeolite.
 6. The method of claim 5 wherein the molecular sieve iszeolite beta, ZSM-5, SSZ-25, SM-3, SSZ-32, SSZ-13, SSZ-33 or ZSM-23. 7.The method of claim 2 wherein the microporous solid is analuminophosphate or silicoaluminophosphate.
 8. The method of claim 1wherein the temperature at which the structure directing agent isremoved is below 300° C.
 9. The method of claim 1 wherein the structuredirecting agent can not be removed from the pores of the molecular sieveby solvent extraction prior to cleaving it.
 10. The method of claim 1further comprising recovering the fragments of the cleaved structuredirecting agent and restoring it to its original chemical structure. 11.The method of claim 1 wherein the structure directing agent is anammonium-acetal.
 12. The method of claim 11 wherein the ammonium-acetalhas the general formula

where R¹, R² and R³ are each independently lower alkyl and R⁴ and R⁵ areeach independently lower alkyl.
 13. The method of claim 11 wherein theammonium-acetal has the general formula

where R⁶ and R⁷ are each independently lower alkyl, or R⁶ and R⁷together form a five or six membered, substituted or unsubstituted ringwith the nitrogen atom, and R⁸ and R⁹ are each independently loweralkyl, or R⁸ and R⁹ together are —CH₂CH₂— and form a five membered ring.14. The method of claim 12 wherein the ammonium-acetal is


15. The method of claim 13 wherein the ammonium-acetal is


16. The method of claim 13 wherein the ammonium acetal is


17. The method of claim 10 wherein the cleaved structure directing agentcomprises an ammonium-diol compound, and it is restored to its originalammonium-acetal chemical structure by reaction with an alcohol.
 18. Amethod of removing a structure directing agent from a porous molecularsieve at a temperature below the temperature that would cause thestructure directing agent to decompose comprising cleaving the structuredirecting agent within the pores of the molecular sieve, at atemperature below the temperature that would cause the structuredirecting agent to decompose, into two or more fragments and removingthe fragments from the pores of the molecular sieve at a temperaturebelow the temperature that would cause the structure directing agent orits fragments to decompose.
 19. The method of claim 18 wherein thetemperature at which the structure directing agent is removed is below300° C.
 20. The method of claim 18 wherein the structure directing agentcan not be removed from the pores of the molecular sieve by solventextraction prior to cleaving it.
 21. The method of claim 18 furthercomprising recovering the fragments of the cleaved structure directingagent and restoring it to its original chemical structure.
 22. Themethod of claim 18 wherein the structure directing agent is anammonium-acetal.
 23. The method of claim 22 wherein the ammonium-acetalhas the general formula

where R¹, R² and R³ are each independently lower alkyl and R⁴ and R⁵ areeach independently lower alkyl.
 24. The method of claim 22 wherein theammonium-acetal has the general formula

where R⁶ and R⁷ are each independently lower alkyl, or R⁶ and R⁷together form a five or six membered, substituted or unsubstituted ringwith the nitrogen atom, and R⁸ and R⁹ are each independently loweralkyl, or R⁸ and R⁹ together are —CH₂CH₂— and form a five membered ring.25. The method of claim 23 wherein the ammonium-acetal is


26. The method of claim 24 wherein the ammonium-acetal is


27. The method of claim 24 wherein the ammonium acetal is


28. The method of claim 21 wherein the cleaved structure directing agentcomprises an ammonium-diol compound, and it is restored to its originalammonium-acetal chemical structure by reaction with an alcohol.
 29. Themethod of claim 18 wherein the molecular sieve is a zeolite.
 30. Themethod of claim 18 wherein the molecular sieve is zeolite beta, ZSM-5,SSZ-25, SM-3, SSZ-32, SSZ-13, SSZ-33 or ZSM-23.
 31. The method of claim18 wherein the molecular sieve is an aluminophosphate orsilicoaluminophosphate.
 32. A method of making a porous, crystallinemolecular sieve comprising: (a) preparing an aqueous solution from (1)sources of an alkali metal oxide, alkaline earth metal oxide or mixturesthereof; (2) sources of an oxide selected from the oxides of aluminum,iron, gallium, indium, titanium, or mixtures thereof; (3) sources of anoxide selected from oxides of silicon, germanium or mixtures thereof;and (4) a structure directing agent capable of forming the molecularsieve; (b) maintaining the aqueous solution under conditions sufficientto form porous crystals of the molecular sieve which contain thestructure directing agent in the pores; and (c) cleaving the structuredirecting agent, at a temperature below the temperature that would causethe structure directing agent to decompose, into two or more fragmentsand removing the fragments from the molecular sieve at a temperaturebelow the temperature that would cause the structure directing agent orits fragments to decompose.
 33. The method of claim 32 wherein thetemperature in step (c) is below 300° C.
 34. The method of claim 32wherein the structure directing agent can not be removed from the poresof the molecular sieve by solvent extraction prior to cleaving it. 35.The method of claim 32 further comprising recovering the fragments ofthe cleaved structure directing agent and restoring it to its originalchemical structure.
 36. The method of claim 32 wherein the molecularsieve is a zeolite.
 37. The method of claim 32 wherein the molecularsieve is zeolite beta, ZSM-5, SSZ-25, SM-3, SSZ-32, SSZ-13, SSZ-33 orZSM-23.
 38. The method of claim 32 wherein the molecular sieve is analuminophosphate or silicoaluminophosphate.
 39. The method of claim 32wherein the structure directing agent is an ammonium-acetal.
 40. Themethod of claim 39 wherein the ammonium-acetal has the general formula

where R¹, R² and R³ are each independently lower alkyl and R⁴ and R⁵ areeach independently lower alkyl.
 41. The method of claim 39 wherein theammonium-acetal has the general formula

where R⁶ and R⁷ are each independently lower alkyl, or R⁶ and R⁷together form a five or six membered, substituted or unsubstituted ringwith the nitrogen atom, and R⁸ and R⁹ are each independently loweralkyl, or R⁸ and R⁹ together are —CH₂CH₂— and form a five membered ring.42. The method of claim 40 wherein the ammonium-acetal is


43. The method of claim 41 wherein the ammonium-acetal is


44. The method of claim 41 wherein the ammonium acetal is


45. The method of claim 35 wherein the cleaved structure directing agentcomprises an ammonium-diol compound, and it is restored to its originalammonium-acetal chemical structure by reaction with an alcohol.
 46. Amethod of making a porous, crystalline molecular sieve comprising: (a)preparing an aqueous solution from (1) sources of an alkali metal oxide,alkaline earth metal oxide or mixtures thereof; (2) sources of an oxideselected from the oxides of aluminum, iron, gallium, indium, titanium,or mixtures thereof; (3) sources of an oxide selected from oxides ofsilicon, germanium or mixtures thereof; and (4) a structure directingagent capable of forming the molecular sieve; and (5) an amine componentcomprising at least one amine containing one to eight carbon atoms,ammonium hydroxide and mixtures thereof; (b) maintaining the aqueoussolution under conditions sufficient to form porous crystals of themolecular sieve which contain the structure directing agent and theamine component in the pores; (c) removing the amine component from thepores of the molecular sieve at a temperature below the temperature thatwould cause the structure directing agent or the amine component todecompose; and (d) cleaving the structure directing agent, at atemperature below the temperature that would cause the structuredirecting agent to decompose, into two or more fragments and removingthe fragments from the molecular sieve at a temperature below thetemperature that would cause the structure directing agent or itsfragments to decompose.
 47. The method of claim 46 wherein the structuredirecting agent is an ammonium-acetal compound.
 48. The method of claim47 wherein the ammonium-acetal has the general formula

where R¹, R² and R³ are each independently lower alkyl and R⁴ and R⁵ areeach independently lower alkyl.
 49. The method of claim 47 wherein theammonium-acetal has the general formula

where R⁶ and R⁷ are each independently lower alkyl, or R⁶ and R⁷together form a five or six membered, substituted or unsubstituted ringwith the nitrogen atom, and R⁸ and R⁹ are each independently loweralkyl, or R⁸ and R⁹ together are —CH₂CH₂— and form a five membered ring.50. The method of claim 48 wherein the ammonium-acetal is


51. The method of claim 49 wherein the ammonium-acetal is


52. The method of claim 49 wherein the ammonium acetal is


53. The method of claim 46 further comprising recovering the fragmentsof the cleaved structure directing agent and restoring it to itsoriginal chemical structure.
 54. The method of claim 53 wherein thecleaved structure directing agent comprises an ammonium-diol compound,and it is restored to its original ammonium-acetal chemical structure byreaction with an alcohol.
 55. The method of claim 46 wherein the aminecomponent is isopropylamine, isobutylamine, n-butylamine, piperidine,4-methylpiperidine, cyclohexylamine, 1,1,3,3-tetramethyl butylamine, orcyclopentylamine.
 56. The method of claim 55 wherein the amine componentis isobutylamine.
 57. The method of claim 46 wherein the wherein theamine component is removed by solvent extraction.
 58. The method ofclaim 57 wherein the solvent is dimethylformamide.
 59. The method ofclaim 57 wherein the solvent is ethylene glycol.
 60. The method of claim46 wherein the molecular sieve is a zeolite.
 61. The method of claim 46wherein the molecular sieve is zeolite beta, ZSM-5, SSZ-25, SM-3,SSZ-32, SSZ-13, SSZ-33 or ZSM-23..
 62. The method of claim 46 whereinthe molecular sieve is an aluminophosphate or silicoaluminophosphate.63. A method of making a microporous solid comprising: (a) preparing areaction mixture comprising at least one active source of reactantsrequired to produce the microporous solid, a structure directing agentcapable of forming said microporous solid, and sufficient water to shapesaid mixture into a self-supporting shape; (b) heating said reactionmixture at crystallization conditions and in the absence of an externalliquid phase for sufficient time to form the microporous solidcontaining the structure directing agent; and (c) cleaving the structuredirecting agent, at a temperature below the temperature that would causethe structure directing agent to decompose, into two or more fragmentsand removing the fragments from the molecular sieve at a temperaturebelow the temperature that would cause the structure directing agent orits fragments to decompose.
 64. The method of claim 63 wherein thetemperature in step (c) is below 300° C.
 65. The method of claim 63wherein the structure directing agent can not be removed from the poresof the microporous solid by solvent extraction prior to cleaving it. 66.The method of claim 63 further comprising recovering the fragments ofthe cleaved structure directing agent and restoring it to its originalchemical structure.
 67. The method of claim 63 wherein the microporoussolid is an inorganic oxide, inorganic sulfide, molecular sieve,zeolite, aluminophosphate, silicoaluminophosphate or heteropolytungstate.
 68. The method of claim 63 wherein the microporous solidis a molecular sieve.
 69. The method of claim 63 wherein the microporoussolid is a zeolite.
 70. The method of claim 68 wherein the molecularsieve is zeolite beta, ZSM-5, SSZ-25, SM-3, SSZ-32, SSZ-13, SSZ-33 orZSM-23.
 71. The method of claim 68 wherein the molecular sieve is analuminophosphate or silicoaluminophosphate.
 72. The method of claim 63wherein the structure directing agent is an ammonium-acetal.
 73. Themethod of claim 72 wherein the ammonium-acetal has the general formula

where R¹, R² and R³ are each independently lower alkyl and R⁴ and R⁵ areeach independently lower alkyl.
 74. The method of claim 72 wherein theammonium-acetal has the general formula where R⁶ and R⁷ are eachindependently lower alkyl, or R⁶ and R⁷ together form a five or sixmembered, substituted or unsubstituted ring with the nitrogen atom, andR8 and R⁹ are

each independently lower alkyl, or R⁸ and R⁹ together are —CH₂CH₂— andform a five membered ring.
 75. The method of claim 73 wherein theammonium-acetal is


76. The method of claim 74 wherein the ammonium-acetal is


77. The method of claim 74 wherein the ammonium acetal is


78. The method of claim 66 wherein the cleaved structure directing agentcomprises an ammonium-diol compound, and it is restored to its originalammonium-acetal chemical structure by reaction with an alcohol.
 79. Amethod of making a microporous solid comprising: (a) preparing areaction mixture comprising at least one active source of reactantsrequired to produce the microporous solid, a structure directing agentcapable of forming said microporous solid, an amine component comprisingat least one amine containing one to eight carbon atoms, ammoniumhydroxide and mixtures thereof, and sufficient water to shape saidmixture into a self-supporting shape; (b) heating said reaction mixtureat crystallization conditions and in the absence of an external liquidphase for sufficient time to form the microporous solid containing thestructure directing agent and the amine component; and (c) removing theamine component from the pores of the molecular sieve at a temperaturebelow the temperature that would cause the structure directing agent orthe amine component to decompose; and (d) cleaving the structuredirecting agent, at a temperature below the temperature that would causethe structure directing agent to decompose, into two or more fragmentsand removing the fragments from the molecular sieve at a temperaturebelow the temperature that would cause the structure directing agent orits fragments to decompose.
 80. The method of claim 79 wherein thetemperature in step (c) is below 300° C.
 81. The method of claim 79wherein the structure directing agent can not be removed from the poresof the microporous solid by solvent extraction prior to cleaving it. 82.The method of claim 79 further comprising recovering the fragments ofthe cleaved structure directing agent and restoring it to its originalchemical structure.
 83. The method of claim 79 wherein the microporoussolid is an inorganic oxide, inorganic sulfide, molecular sieve,zeolite, aluminophosphate, silicoaluminophosphate or heteropolytungstate.
 84. The method of claim 79 wherein the microporous solidis a molecular sieve.
 85. The method of claim 79 wherein the microporoussolid is a zeolite.
 86. The method of claim 84 wherein the molecularsieve is zeolite beta, ZSM-5, SSZ-25, SM-3, SSZ-32, SSZ-13, SSZ-33 orZSM-23.
 87. The method of claim 84 wherein the molecular sieve is analuminophosphate or silicoaluminophosphate.
 88. The method of claim 79wherein the structure directing agent is an ammonium-acetal compound.89. The method of claim 88 wherein the ammonium-acetal has the generalformula

where R¹, R² and R³ are each independently lower alkyl and R⁴ and R⁵ areeach independently lower alkyl.
 90. The method of claim 88 wherein theammonium-acetal has the general formula

where R⁶ and R⁷ are each independently lower alkyl, or R⁶ and R⁷together form a five or six membered, substituted or unsubstituted ringwith the nitrogen atom, and R⁸ and R⁹ are each independently loweralkyl, or R⁸ and R⁹ together are —CH₂CH₂— and form a five membered ring.91. The method of claim 89 wherein the ammonium-acetal is


92. The method of claim 90 wherein the ammonium-acetal is


93. The method of claim 90 wherein the ammonium acetal is


94. The method of claim 79 further comprising recovering the fragmentsof the cleaved structure directing agent and restoring it to itsoriginal chemical structure.
 95. The method of claim 94 wherein thecleaved structure directing agent comprises an ammonium-diol compound,and it is restored to its original ammonium-acetal chemical structure byreaction with an alcohol.
 96. The method of claim 79 wherein the aminecomponent is isopropylamine, isobutylamine, n-butylamine, piperidine,4-methylpiperidine, cyclohexylamine, 1,1,3,3-tetramethyl butylamine, orcyclopentylamine.
 97. The method of claim 96 wherein the amine componentis isobutylamine.
 98. The method of claim 79 wherein the wherein theamine component is removed by solvent extraction.
 99. The method ofclaim 98 wherein the solvent is dimethylformamide.
 100. The method ofclaim 98 wherein the solvent is ethylene glycol.